on (someone's or something's) (own) merits
Objectively based on or due to someone's or something's actual qualities, actions, etc. (as opposed to other, less objective factors). I can assure you that she got the job on her own merits and not because she is the CEO's daughter.
on its merits
Also, on one's merits or according to one's merits . With regard only to the intrinsic quality of something or someone. For example, Who supports it doesn't matter; we have to consider the idea solely on its merits, or The agency doesn't care about her references but wants to hire candidates according to their merits . [Late 1800s]